Properties of Pyranyl Foams

Mechanical properties, thermal conductivity, thermal stability, flame retardance and chemical resistance are shown below. 

Mechanical Properties. Some physical strengths of 2.2 pcf overalldensity. Foam core density 1.8 pcf are shown in Table 32 (1). 

Perpendicular to direction of flow Parallel to direction of flow 

Compressive-strength values are generally of the same order as the tensile strengths in the 2.0- to 3.0-pcf overall-density region. More important is the isotropic nature of the foam, which indicates rounded cells which have almost the same compressive strengths in both parallel and perpendicular directions to foam rise. This is very important in providing dimensionally stable foams. 

In rigid urethane foams, the cell shapes are elliptical like eggs, and, therefore, the compressive strengths in the direction perpendicular to foam rise is smaller than the direction parallel to foam rise. Therefore, if urethane foams are required to have the same compressive strength as pyranyl foams in the direction perpendicular to foam rise (i.e., compressive strength in the direction vertical to the panel substrate) urethane foams must have foam densities greater than those of pyranyl foams. Adhesion of pyranyl foams to various substrates, e.g., steel, phosphated steel, stainless steel and aluminum, as well as paper and wood, is very good. 

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Chemical Resistance. Table 35 shows some of the chemical resistance properties of pyranyl foams. The table shows that pyranyl foams are stable in polar and non-polar solvents. 

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